Tripawd limb cancer treatments can involve many different strategies. These may include non-surgical treatments. For the second part of our interview series about treating leg cancers in dogs and cats, we discuss bisphosphonates and a “targeted therapy” drug called Palladia.
Your expert today is once again Dr. Bernard Séguin, DVM, MS, Diplomate ACVS, ACVS Founding Fellow – Surgical Oncology and Associate Professor, Surgical Oncology at Colorado State University Flint Animal Cancer Center.
Bisphosphonates Help Tripawds with Limb Cancer Treatments
How can a drug treatment originally used to prevent bone loss in people help pets with a limb cancer? Dr. Séguin explains how bisphosphonates can be used in pets who aren’t good candidates for amputation surgery, like Hazel the Great Dane. Sometimes bisphosponates can be used for those who do have a leg removed, including Simon the German Shepherd.
What are Bisphosphonates?
Question: Tell us about bisphosphonates.
Dr. Séguin: So bisphosphonates are a family of drugs. There are several members in that family, Fosamax maybe one that people maybe more familiar with because you may see ads for Fosamax. The ones that have been used in vet medicine are mostly Pamidronate and Zoledronate.
I think as a professional, we are shifting more towards Zoledronate. It maybe better although the evidence is lacking in a way. We don’t have very much evidence that Zoledronate is really better than Pamidronate.
Basically bisphosphonates, what they are is a classic drug in the way that they inhibit a type of cell called the osteoclast. And the osteoclast is responsible for destroying the bone. So if we can inhibit that then the bone may get stronger.
There is also some evidence that it may have anticancer properties. But there again, the evidence, I don’t think we’ve ever shown this in a live animal. So basically, we give these drugs with the intent of slowing down and maybe even stopping the destruction of the bone.
It can be used by itself. It can be combined with radiation therapy. Certainly if we’re doing an amputation, there isn’t really a justification for using it. We’ve just removed the tumor, and we are talking about bone tumors.
And so, either with radiation or by itself, and there again, when it comes down to the evidence, we don’t have very much evidence that it has – that it works great. But it seems that it can help some dogs and I think it’s worthwhile trying to see if it’s going to work in an individual dog.
And then in terms of combining it with radiation therapy, there are actually conflicting evidences as to in some studies, it helps, in other studies, it actually did not help, or even in one study, made things worse. So we have to be careful. I think that we need to learn more but for a time being, we do recommend it with the caveat that we don’t know how effective it truly is.
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How Can Palladia Targeted Therapy Fight Pet Cancer?
How is Palladia (Toceranib phosphate) Used in Pet Cancer Treatment?
Question: Can you tell me more about Palladia?
Dr. Séguin: Palladia is what we call targeted therapy. The scientific name is what we call tyrosine kinase inhibitors so it goes to a very, very specific receptor in the cell. And by doing so, it can actually kill the cell. And I guess you could say more tumor cells expressed that receptor or maybe the tumor cell is more sensitive to that drug. What we hope to do is to be more targeted in our approach to killing the tumor cells and try to spare the normal cells.
It’s not without side effects, but the idea is that you may be better able to spare the normal cells and really go after the tumor cells that can express the receptor and maybe even sometimes have mutation in that receptor.
Palladia goes to that receptor and then once it binds there, it can lead to the death of the cell. So that’s the idea behind Palladia.
Question: Who is the ideal candidate for Palladia and when?
Dr. Séguin: For now, Palladia has been studied the most in dogs with muscle tumors. And so I would say that’s probably the cancer where it’s being used the most. But it has also been looked in other types of cancer, one of which being osteosarcoma and I would say thyroid tumors and there’s a number of other tumors.
And the reality is that sometimes we come to a point where we’ve exhausted what we think might work and then we say, “Let’s try Palladia.” So sometimes there’s not necessarily good evidence that it’s going to work but we are at a point where we say, “Let’s give it a try and see what happens.”
Question: How is Palladia administered?
Dr. Séguin: Palladia is an oral medication.
[End of transcript]
Stay tuned for next week’s third and final Tripawd limb cancer treatments video series with Dr. Séguin.
Many thanks to the rock star oncology team at the Flint Animal Cancer Center at Colorado State University for generously allowing us to visit and share this information with the Tripawds community.